R=120;
C=33e-12;
tau=R*C;
tau
T=tau/100;
t=0:T:3*tau;
M=length(t);
T
M
U(1)=0;
E=1;
for k=2:M
    U(k)=U(k-1)-(T/tau)*U(k-1)+(E*T)/tau
end
plot(t,U)